The present invention relates to a rotary vane machine having a rotor with sliding vanes that are guided for non-contact sealing movement between the vane tips and an interior casing sidewall. In particular, the present invention relates to sealing plates positioned on both ends of the rotor to improve sealing of the rotor with interior casing end walls.
Rotary vane machines are known and have been described for example in U.S. Pat. Nos. 5,087,183 and 5,160,252. The rotary vane machines described in these references includes a cylindrical rotor equipped with one or more tethered sliding vanes wherein the rotor is positioned eccentrically inside a housing. The housing defines an enclosed chamber with opposed end surfaces. As the rotor rotates about its axis, fluid received from an inlet is compressed and discharged out an outlet.
Although the rotary vane machine provides an efficient pump to suit many applications, components of the rotary vane machine must be manufactured with extreme precision in order for the machine to operate effectively. Particularly, the rotor must be positioned within the chamber of the housing with end surfaces close to, but not contacting, inner end surfaces of the housing. If manufactured correctly, the rotor will not contact the inner end surfaces of the housing, but rather, will allow oil to be located therebetween to provide a continuous annular seal for the chamber as the rotor rotates. Typically, bearing assemblies are provided in annular recesses formed in the opposed end surfaces. The bearing assemblies allow rotation of the tether assemblies about the rotor axis. In order to extend the annular sealing surfaces of the housing opposing the end surfaces of the rotor, outer races of the bearing assemblies must be machined after the bearing assemblies have been installed to provide a smooth inner annular surface opposing each of the rotor end surfaces. This method of manufacture is both difficult and time consuming, thus increasing the cost of the machine.